diff options
Diffstat (limited to 'examples')
| -rw-r--r-- | examples/afl_frida/Makefile | 23 | ||||
| -rw-r--r-- | examples/afl_frida/README.md | 34 | ||||
| -rw-r--r-- | examples/afl_frida/afl-frida.c | 541 | ||||
| -rw-r--r-- | examples/afl_frida/afl-frida.h | 53 | ||||
| -rw-r--r-- | examples/afl_frida/libtestinstr.c | 35 | ||||
| -rw-r--r-- | examples/afl_network_proxy/afl-network-client.c | 4 | ||||
| -rw-r--r-- | examples/afl_untracer/README.md | 3 | ||||
| -rw-r--r-- | examples/afl_untracer/TODO | 2 | ||||
| -rw-r--r-- | examples/afl_untracer/afl-untracer.c | 24 | ||||
| -rw-r--r-- | examples/custom_mutators/post_library_gif.so.c | 2 | ||||
| -rw-r--r-- | examples/defork/Makefile | 64 | ||||
| -rw-r--r-- | examples/defork/README.md | 11 | ||||
| -rw-r--r-- | examples/defork/defork.c | 50 | ||||
| -rwxr-xr-x | examples/defork/forking_target | bin | 0 -> 19520 bytes | |||
| -rw-r--r-- | examples/defork/forking_target.c | 48 |
15 files changed, 884 insertions, 10 deletions
diff --git a/examples/afl_frida/Makefile b/examples/afl_frida/Makefile new file mode 100644 index 00000000..c154f3a4 --- /dev/null +++ b/examples/afl_frida/Makefile @@ -0,0 +1,23 @@ +ifdef DEBUG + OPT=-O0 -D_DEBUG=\"1\" +else + OPT=-O3 -funroll-loops +endif + +all: afl-frida libtestinstr.so + +libfrida-gum.a: + @echo Download and extract frida-gum-devkit-VERSION-PLATFORM.tar.xz for your platform from https://github.com/frida/frida/releases/latest + @exit 1 + +afl-frida: afl-frida.c libfrida-gum.a + $(CC) -g $(OPT) -o afl-frida -Wno-format -Wno-pointer-sign -I. -fpermissive -fPIC afl-frida.c ../../afl-llvm-rt.o libfrida-gum.a -ldl -lresolv -pthread + +libtestinstr.so: libtestinstr.c + $(CC) -g -O0 -fPIC -o libtestinstr.so -shared libtestinstr.c + +clean: + rm -f afl-frida *~ core *.o libtestinstr.so + +deepclean: clean + rm -f libfrida-gum.a frida-gum* diff --git a/examples/afl_frida/README.md b/examples/afl_frida/README.md new file mode 100644 index 00000000..7743479b --- /dev/null +++ b/examples/afl_frida/README.md @@ -0,0 +1,34 @@ +# afl-frida - faster fuzzing of binary-only libraries + +## Introduction + +afl-frida is an example skeleton file which can easily be used to fuzz +a closed source library. + +It requires less memory and is x5-10 faster than qemu_mode but does not +provide interesting features like compcov or cmplog. + +## How-to + +### Modify afl-frida.c + +Read and modify afl-frida.c then `make`. +To adapt afl-frida.c to your needs, read the header of the file and then +search and edit the `STEP 1`, `STEP 2` and `STEP 3` locations. + +### Fuzzing + +Example (after modifying afl-frida.c to your needs and compile it): +``` +LD_LIBRARY_PATH=/path/to/the/target/library afl-fuzz -i in -o out -- ./afl-frida +``` +(or even remote via afl-network-proxy). + +# Speed and stability + +The speed is very good, about x12 of fork() qemu_mode. +However the stability is low. Reason is currently unknown. + +# Background + +This code is copied for a larger part from https://github.com/meme/hotwax diff --git a/examples/afl_frida/afl-frida.c b/examples/afl_frida/afl-frida.c new file mode 100644 index 00000000..2ad5a72a --- /dev/null +++ b/examples/afl_frida/afl-frida.c @@ -0,0 +1,541 @@ +/* + american fuzzy lop++ - afl-frida skeleton example + ------------------------------------------------- + + Copyright 2020 AFLplusplus Project. All rights reserved. + + Written mostly by meme -> https://github.com/meme/hotwax + + Modificationy by Marc Heuse <mh@mh-sec.de> + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at: + + http://www.apache.org/licenses/LICENSE-2.0 + + HOW-TO + ====== + + You only need to change the following: + + 1. set the defines and function call parameters. + 2. dl load the library you want to fuzz, lookup the functions you need + and setup the calls to these. + 3. in the while loop you call the functions in the necessary order - + incl the cleanup. the cleanup is important! + + Just look these steps up in the code, look for "// STEP x:" + +*/ + +#include <stdio.h> +#include <stdint.h> +#include <unistd.h> +#include <stdint.h> +#include <stddef.h> +#include <sys/shm.h> +#include <dlfcn.h> + +#ifndef __APPLE__ + #include <sys/wait.h> + #include <sys/personality.h> +#endif + +int debug = 0; + +// STEP 1: + +// The presets are for the example libtestinstr.so: + +/* What is the name of the library to fuzz */ +#define TARGET_LIBRARY "libtestinstr.so" + +/* What is the name of the function to fuzz */ +#define TARGET_FUNCTION "testinstr" + +/* here you need to specify the parameter for the target function */ +static void *(*o_function)(uint8_t *, int); + +// END STEP 1 + +#include "frida-gum.h" + +G_BEGIN_DECLS + +#define GUM_TYPE_FAKE_EVENT_SINK (gum_fake_event_sink_get_type()) +G_DECLARE_FINAL_TYPE(GumFakeEventSink, gum_fake_event_sink, GUM, + FAKE_EVENT_SINK, GObject) + +struct _GumFakeEventSink { + + GObject parent; + GumEventType mask; + +}; + +GumEventSink *gum_fake_event_sink_new(void); +void gum_fake_event_sink_reset(GumFakeEventSink *self); + +G_END_DECLS + +static void gum_fake_event_sink_iface_init(gpointer g_iface, + gpointer iface_data); +static void gum_fake_event_sink_finalize(GObject *obj); +static GumEventType gum_fake_event_sink_query_mask(GumEventSink *sink); +static void gum_fake_event_sink_process(GumEventSink *sink, const GumEvent *ev); +void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output, + gpointer user_data); +void afl_setup(void); +void afl_start_forkserver(void); +int __afl_persistent_loop(unsigned int max_cnt); + +static void gum_fake_event_sink_class_init(GumFakeEventSinkClass *klass) { + + GObjectClass *object_class = G_OBJECT_CLASS(klass); + object_class->finalize = gum_fake_event_sink_finalize; + +} + +static void gum_fake_event_sink_iface_init(gpointer g_iface, + gpointer iface_data) { + + GumEventSinkInterface *iface = (GumEventSinkInterface *)g_iface; + iface->query_mask = gum_fake_event_sink_query_mask; + iface->process = gum_fake_event_sink_process; + +} + +G_DEFINE_TYPE_EXTENDED(GumFakeEventSink, gum_fake_event_sink, G_TYPE_OBJECT, 0, + G_IMPLEMENT_INTERFACE(GUM_TYPE_EVENT_SINK, + gum_fake_event_sink_iface_init)) + +#include "../../config.h" + +// Shared memory fuzzing. +int __afl_sharedmem_fuzzing = 1; +extern unsigned int * __afl_fuzz_len; +extern unsigned char *__afl_fuzz_ptr; + +// Notify AFL about persistent mode. +static volatile char AFL_PERSISTENT[] = "##SIG_AFL_PERSISTENT##"; +int __afl_persistent_loop(unsigned int); + +// Notify AFL about deferred forkserver. +static volatile char AFL_DEFER_FORKSVR[] = "##SIG_AFL_DEFER_FORKSRV##"; +void __afl_manual_init(); + +// Because we do our own logging. +extern uint8_t * __afl_area_ptr; +static __thread guint64 previous_pc; + +// Frida stuff below. +typedef struct { + + GumAddress base_address; + guint64 code_start, code_end; + +} range_t; + +inline static void afl_maybe_log(guint64 current_pc) { + + // fprintf(stderr, "PC: %p ^ %p\n", current_pc, previous_pc); + + current_pc = (current_pc >> 4) ^ (current_pc << 8); + current_pc &= MAP_SIZE - 1; + + __afl_area_ptr[current_pc ^ previous_pc]++; + previous_pc = current_pc >> 1; + +} + +static void on_basic_block(GumCpuContext *context, gpointer user_data) { + + afl_maybe_log((guint64)user_data); + +} + +void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output, + gpointer user_data) { + + range_t *range = (range_t *)user_data; + + const cs_insn *instr; + gboolean begin = TRUE; + while (gum_stalker_iterator_next(iterator, &instr)) { + + if (begin) { + + if (instr->address >= range->code_start && + instr->address <= range->code_end) { + + gum_stalker_iterator_put_callout(iterator, on_basic_block, + (gpointer)instr->address, NULL); + begin = FALSE; + + } + + } + + gum_stalker_iterator_keep(iterator); + + } + +} + +static void gum_fake_event_sink_init(GumFakeEventSink *self) { + +} + +static void gum_fake_event_sink_finalize(GObject *obj) { + + G_OBJECT_CLASS(gum_fake_event_sink_parent_class)->finalize(obj); + +} + +GumEventSink *gum_fake_event_sink_new(void) { + + GumFakeEventSink *sink; + sink = (GumFakeEventSink *)g_object_new(GUM_TYPE_FAKE_EVENT_SINK, NULL); + return GUM_EVENT_SINK(sink); + +} + +void gum_fake_event_sink_reset(GumFakeEventSink *self) { + +} + +static GumEventType gum_fake_event_sink_query_mask(GumEventSink *sink) { + + return 0; + +} + +typedef struct library_list { + + uint8_t *name; + uint64_t addr_start, addr_end; + +} library_list_t; + +#define MAX_LIB_COUNT 256 +static library_list_t liblist[MAX_LIB_COUNT]; +static u32 liblist_cnt; + +void read_library_information() { + +#if defined(__linux__) + FILE *f; + u8 buf[1024], *b, *m, *e, *n; + + if ((f = fopen("/proc/self/maps", "r")) == NULL) { + + fprintf(stderr, "Error: cannot open /proc/self/maps\n"); + exit(-1); + + } + + if (debug) fprintf(stderr, "Library list:\n"); + while (fgets(buf, sizeof(buf), f)) { + + if (strstr(buf, " r-x")) { + + if (liblist_cnt >= MAX_LIB_COUNT) { + + fprintf( + stderr, + "Warning: too many libraries to old, maximum count of %d reached\n", + liblist_cnt); + return; + + } + + b = buf; + m = index(buf, '-'); + e = index(buf, ' '); + if ((n = rindex(buf, '/')) == NULL) n = rindex(buf, ' '); + if (n && + ((*n >= '0' && *n <= '9') || *n == '[' || *n == '{' || *n == '(')) + n = NULL; + else + n++; + if (b && m && e && n && *n) { + + *m++ = 0; + *e = 0; + if (n[strlen(n) - 1] == '\n') n[strlen(n) - 1] = 0; + + if (rindex(n, '/') != NULL) { + + n = rindex(n, '/'); + n++; + + } + + liblist[liblist_cnt].name = strdup(n); + liblist[liblist_cnt].addr_start = strtoull(b, NULL, 16); + liblist[liblist_cnt].addr_end = strtoull(m, NULL, 16); + if (debug) + fprintf( + stderr, "%s:%llx (%llx-%llx)\n", liblist[liblist_cnt].name, + liblist[liblist_cnt].addr_end - liblist[liblist_cnt].addr_start, + liblist[liblist_cnt].addr_start, + liblist[liblist_cnt].addr_end - 1); + liblist_cnt++; + + } + + } + + } + + if (debug) fprintf(stderr, "\n"); + +#elif defined(__FreeBSD__) + int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_VMMAP, getpid()}; + char * buf, *start, *end; + size_t miblen = sizeof(mib) / sizeof(mib[0]); + size_t len; + + if (debug) fprintf(stderr, "Library list:\n"); + if (sysctl(mib, miblen, NULL, &len, NULL, 0) == -1) { return; } + + len = len * 4 / 3; + + buf = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0); + if (buf == MAP_FAILED) { return; } + if (sysctl(mib, miblen, buf, &len, NULL, 0) == -1) { + + munmap(buf, len); + return; + + } + + start = buf; + end = buf + len; + + while (start < end) { + + struct kinfo_vmentry *region = (struct kinfo_vmentry *)start; + size_t size = region->kve_structsize; + + if (size == 0) { break; } + + if ((region->kve_protection & KVME_PROT_READ) && + !(region->kve_protection & KVME_PROT_EXEC)) { + + liblist[liblist_cnt].name = + region->kve_path[0] != '\0' ? strdup(region->kve_path) : 0; + liblist[liblist_cnt].addr_start = region->kve_start; + liblist[liblist_cnt].addr_end = region->kve_end; + + if (debug) { + + fprintf(stderr, "%s:%x (%lx-%lx)\n", liblist[liblist_cnt].name, + liblist[liblist_cnt].addr_end - liblist[liblist_cnt].addr_start, + liblist[liblist_cnt].addr_start, + liblist[liblist_cnt].addr_end - 1); + + } + + liblist_cnt++; + + } + + start += size; + + } + +#endif + +} + +library_list_t *find_library(char *name) { + + char *filename = rindex(name, '/'); + + if (filename) + filename++; + else + filename = name; + +#if defined(__linux__) + u32 i; + for (i = 0; i < liblist_cnt; i++) + if (strcmp(liblist[i].name, filename) == 0) return &liblist[i]; +#elif defined(__APPLE__) && defined(__LP64__) + kern_return_t err; + static library_list_t lib; + + // get the list of all loaded modules from dyld + // the task_info mach API will get the address of the dyld all_image_info + // struct for the given task from which we can get the names and load + // addresses of all modules + task_dyld_info_data_t task_dyld_info; + mach_msg_type_number_t count = TASK_DYLD_INFO_COUNT; + err = task_info(mach_task_self(), TASK_DYLD_INFO, + (task_info_t)&task_dyld_info, &count); + + const struct dyld_all_image_infos *all_image_infos = + (const struct dyld_all_image_infos *)task_dyld_info.all_image_info_addr; + const struct dyld_image_info *image_infos = all_image_infos->infoArray; + + for (size_t i = 0; i < all_image_infos->infoArrayCount; i++) { + + const char * image_name = image_infos[i].imageFilePath; + mach_vm_address_t image_load_address = + (mach_vm_address_t)image_infos[i].imageLoadAddress; + if (strstr(image_name, name)) { + + lib.name = name; + lib.addr_start = (u64)image_load_address; + lib.addr_end = 0; + return &lib; + + } + + } + +#endif + + return NULL; + +} + +static void gum_fake_event_sink_process(GumEventSink * sink, + const GumEvent *ev) { + +} + +/* Because this CAN be called more than once, it will return the LAST range */ +static int enumerate_ranges(const GumRangeDetails *details, + gpointer user_data) { + + GumMemoryRange *code_range = (GumMemoryRange *)user_data; + memcpy(code_range, details->range, sizeof(*code_range)); + return 0; + +} + +int main() { + +#ifndef __APPLE__ + (void)personality(ADDR_NO_RANDOMIZE); // disable ASLR +#endif + + // STEP 2: load the library you want to fuzz and lookup the functions, + // inclusive of the cleanup functions. + // If there is just one function, then there is nothing to change + // or add here. + + void *dl = dlopen(TARGET_LIBRARY, RTLD_LAZY); + if (!dl) { + + fprintf(stderr, "Could not load %s\n", TARGET_LIBRARY); + exit(-1); + + } + + if (!(o_function = dlsym(dl, TARGET_FUNCTION))) { + + fprintf(stderr, "Could not find function %s\n", TARGET_FUNCTION); + exit(-1); + + } + + // END STEP 2 + + read_library_information(); + library_list_t *lib = find_library(TARGET_LIBRARY); + + if (lib == NULL) { + + fprintf(stderr, "Could not find target library\n"); + exit(-1); + + } + + gum_init_embedded(); + if (!gum_stalker_is_supported()) { + + gum_deinit_embedded(); + return 1; + + } + + GumStalker *stalker = gum_stalker_new(); + + /* + This does not work here as we load a shared library. pretty sure this + would also be easily solvable with frida gum, but I already have all the + code I need from afl-untracer + + GumAddress base_address = gum_module_find_base_address(TARGET_LIBRARY); + GumMemoryRange code_range; + gum_module_enumerate_ranges(TARGET_LIBRARY, GUM_PAGE_RX, enumerate_ranges, + &code_range); + guint64 code_start = code_range.base_address - base_address; + guint64 code_end = (code_range.base_address + code_range.size) - base_address; + range_t instr_range = {base_address, code_start, code_end}; + */ + range_t instr_range = {0, lib->addr_start, lib->addr_end}; + + GumStalkerTransformer *transformer = + gum_stalker_transformer_make_from_callback(instr_basic_block, + &instr_range, NULL); + + GumEventSink *event_sink = gum_fake_event_sink_new(); + + // to ensure that the signatures are not optimized out + memcpy(__afl_area_ptr, (void *)AFL_PERSISTENT, sizeof(AFL_PERSISTENT) + 1); + memcpy(__afl_area_ptr + 32, (void *)AFL_DEFER_FORKSVR, + sizeof(AFL_DEFER_FORKSVR) + 1); + __afl_manual_init(); + + // + // any expensive target library initialization that has to be done just once + // - put that here + // + + gum_stalker_follow_me(stalker, transformer, event_sink); + + while (__afl_persistent_loop(UINT32_MAX) != 0) { + + previous_pc = 0; // Required! + +#ifdef _DEBUG + fprintf(stderr, "CLIENT crc: %016llx len: %u\n", hash64(__afl_fuzz_ptr, *__a + fprintf(stderr, "RECV:"); + for (int i = 0; i < *__afl_fuzz_len; i++) + fprintf(stderr, "%02x", __afl_fuzz_ptr[i]); + fprintf(stderr,"\n"); +#endif + + // STEP 3: ensure the minimum length is present and setup the target + // function to fuzz. + + if (*__afl_fuzz_len > 0) { + + __afl_fuzz_ptr[*__afl_fuzz_len] = 0; // if you need to null terminate + (*o_function)(__afl_fuzz_ptr, *__afl_fuzz_len); + + } + + // END STEP 3 + + } + + gum_stalker_unfollow_me(stalker); + + while (gum_stalker_garbage_collect(stalker)) + g_usleep(10000); + + g_object_unref(stalker); + g_object_unref(transformer); + g_object_unref(event_sink); + gum_deinit_embedded(); + + return 0; + +} + diff --git a/examples/afl_frida/afl-frida.h b/examples/afl_frida/afl-frida.h new file mode 100644 index 00000000..efa3440f --- /dev/null +++ b/examples/afl_frida/afl-frida.h @@ -0,0 +1,53 @@ +extern int is_persistent; + +G_BEGIN_DECLS + +#define GUM_TYPE_FAKE_EVENT_SINK (gum_fake_event_sink_get_type()) + +G_DECLARE_FINAL_TYPE(GumFakeEventSink, gum_fake_event_sink, GUM, + FAKE_EVENT_SINK, GObject) + +struct _GumFakeEventSink { + + GObject parent; + GumEventType mask; + +}; + +GumEventSink *gum_fake_event_sink_new(void); +void gum_fake_event_sink_reset(GumFakeEventSink *self); + +G_END_DECLS + +typedef struct { + + GumAddress base_address; + guint64 code_start, code_end; + +} range_t; + +void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output, + gpointer user_data); +#pragma once + +void afl_setup(void); +void afl_start_forkserver(void); +int __afl_persistent_loop(unsigned int max_cnt); + +inline static inline void afl_maybe_log(guint64 current_pc) { + + extern unsigned int afl_instr_rms; + extern uint8_t * afl_area_ptr; + + static __thread guint64 previous_pc; + + current_pc = (current_pc >> 4) ^ (current_pc << 8); + current_pc &= MAP_SIZE - 1; + + if (current_pc >= afl_instr_rms) return; + + afl_area_ptr[current_pc ^ previous_pc]++; + previous_pc = current_pc >> 1; + +} + diff --git a/examples/afl_frida/libtestinstr.c b/examples/afl_frida/libtestinstr.c new file mode 100644 index 00000000..96b1cf21 --- /dev/null +++ b/examples/afl_frida/libtestinstr.c @@ -0,0 +1,35 @@ +/* + american fuzzy lop++ - a trivial program to test the build + -------------------------------------------------------- + Originally written by Michal Zalewski + Copyright 2014 Google Inc. All rights reserved. + Copyright 2019-2020 AFLplusplus Project. All rights reserved. + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at: + http://www.apache.org/licenses/LICENSE-2.0 + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> + +void testinstr(char *buf, int len) { + + if (len < 1) return; + buf[len] = 0; + + // we support three input cases + if (buf[0] == '0') + printf("Looks like a zero to me!\n"); + else if (buf[0] == '1') + printf("Pretty sure that is a one!\n"); + else + printf("Neither one or zero? How quaint!\n"); + +} + diff --git a/examples/afl_network_proxy/afl-network-client.c b/examples/afl_network_proxy/afl-network-client.c index 5af41055..a2451fdc 100644 --- a/examples/afl_network_proxy/afl-network-client.c +++ b/examples/afl_network_proxy/afl-network-client.c @@ -34,7 +34,9 @@ #include <netinet/ip6.h> #include <arpa/inet.h> #include <sys/mman.h> -#include <sys/shm.h> +#ifndef USEMMAP + #include <sys/shm.h> +#endif #include <sys/wait.h> #include <sys/types.h> #include <sys/socket.h> diff --git a/examples/afl_untracer/README.md b/examples/afl_untracer/README.md index e59792cb..ada0c916 100644 --- a/examples/afl_untracer/README.md +++ b/examples/afl_untracer/README.md @@ -32,13 +32,14 @@ To easily run the scripts without needing to run the GUI with Ghidra: /opt/ghidra/support/analyzeHeadless /tmp/ tmp$$ -import libtestinstr.so -postscript ./ghidra_get_patchpoints.java rm -rf /tmp/tmp$$ ``` +The file is created at `~/Desktop/patches.txt` ### Fuzzing Example (after modifying afl-untracer.c to your needs, compiling and creating patches.txt): ``` -AFL_UNTRACER_FILE=./patches.txt afl-fuzz -i in -o out -- ./afl-untracer +LD_LIBRARY_PATH=/path/to/target/library AFL_UNTRACER_FILE=./patches.txt afl-fuzz -i in -o out -- ./afl-untracer ``` (or even remote via afl-network-proxy). diff --git a/examples/afl_untracer/TODO b/examples/afl_untracer/TODO new file mode 100644 index 00000000..fffffacf --- /dev/null +++ b/examples/afl_untracer/TODO @@ -0,0 +1,2 @@ + * add shmem fuzzing + * add snapshot feature? diff --git a/examples/afl_untracer/afl-untracer.c b/examples/afl_untracer/afl-untracer.c index 664e691c..68658bfd 100644 --- a/examples/afl_untracer/afl-untracer.c +++ b/examples/afl_untracer/afl-untracer.c @@ -56,6 +56,7 @@ #include <sys/shm.h> #include <sys/wait.h> #include <sys/types.h> +#include <sys/personality.h> #if defined(__linux__) #include <sys/ucontext.h> @@ -73,6 +74,9 @@ // STEP 1: +/* here you need to specify the parameter for the target function */ +static void *(*o_function)(u8 *buf, int len); + /* use stdin (1) or a file on the commandline (0) */ static u32 use_stdin = 1; @@ -395,7 +399,7 @@ static void __afl_map_shm(void) { } /* Fork server logic. */ -static void __afl_start_forkserver(void) { +inline static void __afl_start_forkserver(void) { u8 tmp[4] = {0, 0, 0, 0}; u32 status = 0; @@ -411,7 +415,7 @@ static void __afl_start_forkserver(void) { } -static u32 __afl_next_testcase(u8 *buf, u32 max_len) { +inline static u32 __afl_next_testcase(u8 *buf, u32 max_len) { s32 status; @@ -437,7 +441,7 @@ static u32 __afl_next_testcase(u8 *buf, u32 max_len) { } -static void __afl_end_testcase(int status) { +inline static void __afl_end_testcase(int status) { if (write(FORKSRV_FD + 1, &status, 4) != 4) do_exit = 1; // fprintf(stderr, "write2 %d\n", do_exit); @@ -667,12 +671,11 @@ static void sigtrap_handler(int signum, siginfo_t *si, void *context) { } -/* here you need to specify the parameter for the target function */ -static void *(*o_function)(u8 *buf, int len); - /* the MAIN function */ int main(int argc, char *argv[]) { + (void)personality(ADDR_NO_RANDOMIZE); // disable ASLR + pid = getpid(); if (getenv("AFL_DEBUG")) debug = 1; @@ -706,6 +709,9 @@ int main(int argc, char *argv[]) { while (1) { + // instead of fork() we could also use the snapshot lkm or do our own mini + // snapshot feature like in https://github.com/marcinguy/fuzzer + // -> snapshot.c if ((pid = fork()) == -1) PFATAL("fork failed"); if (pid) { @@ -738,7 +744,11 @@ int main(int argc, char *argv[]) { } -static void fuzz() { +#ifndef _DEBUG +inline +#endif + static void + fuzz() { // STEP 3: call the function to fuzz, also the functions you might // need to call to prepare the function and - important! - diff --git a/examples/custom_mutators/post_library_gif.so.c b/examples/custom_mutators/post_library_gif.so.c index 9b76ead5..2d72400c 100644 --- a/examples/custom_mutators/post_library_gif.so.c +++ b/examples/custom_mutators/post_library_gif.so.c @@ -83,7 +83,7 @@ typedef struct post_state { } post_state_t; -void *afl afl_custom_init(void *afl) { +void *afl_custom_init(void *afl) { post_state_t *state = malloc(sizeof(post_state_t)); if (!state) { diff --git a/examples/defork/Makefile b/examples/defork/Makefile new file mode 100644 index 00000000..e8240dba --- /dev/null +++ b/examples/defork/Makefile @@ -0,0 +1,64 @@ +# +# american fuzzy lop++ - defork +# ---------------------------------- +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at: +# +# http://www.apache.org/licenses/LICENSE-2.0 +# + +.PHONY: all install clean + +PREFIX ?= /usr/local +BIN_PATH = $(PREFIX)/bin +HELPER_PATH = $(PREFIX)/lib/afl + +CFLAGS = -fPIC -Wall -Wextra +LDFLAGS = -shared + +UNAME_SAYS_LINUX=$(shell uname | grep -E '^Linux|^GNU' >/dev/null; echo $$?) +UNAME_SAYS_LINUX:sh=uname | grep -E '^Linux|^GNU' >/dev/null; echo $$? + +_LDFLAGS_ADD=$(UNAME_SAYS_LINUX:1=) +LDFLAGS_ADD=$(_LDFLAGS_ADD:0=-ldl) +LDFLAGS += $(LDFLAGS_ADD) + +# on gcc for arm there is no -m32, but -mbe32 +M32FLAG = -m32 +M64FLAG = -m64 + +CC_IS_GCC=$(shell $(CC) --version 2>/dev/null | grep -q gcc; echo $$?) +CC_IS_GCC:sh=$(CC) --version 2>/dev/null | grep -q gcc; echo $$? +CC_IS_ARMCOMPILER=$(shell $(CC) -v 2>&1 >/dev/null | grep -q arm; echo $$?) +CC_IS_ARMCOMPILER:sh=$(CC) -v 2>&1 >/dev/null | grep -q arm; echo $$? + +_M32FLAG=$(CC_IS_GCC)$(CC_IS_ARMCOMPILER) +__M32FLAG=$(_M32FLAG:00=-mbe32) +___M32FLAG=$(__M32FLAG:$(CC_IS_GCC)$(CC_IS_ARMCOMPILER)=-m32) +M32FLAG=$(___M32FLAG) +#ifeq "$(findstring clang, $(shell $(CC) --version 2>/dev/null))" "" +# ifneq (,$(findstring arm, "$(shell $(CC) -v 2>&1 >/dev/null)")) +# M32FLAG = -mbe32 +# endif +#endif + +all: defork32.so defork64.so + +defork32.so: defork.c + -@$(CC) $(M32FLAG) $(CFLAGS) $^ $(LDFLAGS) -o $@ 2>/dev/null || echo "defork32 build failure (that's fine)" + +defork64.so: defork.c + -@$(CC) $(M64FLAG) $(CFLAGS) $^ $(LDFLAGS) -o $@ 2>/dev/null || echo "defork64 build failure (that's fine)" + +install: defork32.so defork64.so + install -d -m 755 $(DESTDIR)$(HELPER_PATH)/ + if [ -f defork32.so ]; then set -e; install -m 755 defork32.so $(DESTDIR)$(HELPER_PATH)/; fi + if [ -f defork64.so ]; then set -e; install -m 755 defork64.so $(DESTDIR)$(HELPER_PATH)/; fi + +target: + ../../afl-clang forking_target.c -o forking_target -Wall -Wextra -Werror + +clean: + rm -f defork32.so defork64.so forking_target diff --git a/examples/defork/README.md b/examples/defork/README.md new file mode 100644 index 00000000..7e950323 --- /dev/null +++ b/examples/defork/README.md @@ -0,0 +1,11 @@ +# defork + +when the target forks, this breaks all normal fuzzing runs. +Sometimes, though, it is enough to just run the child process. +If this is the case, then this LD_PRELOAD library will always return 0 on fork, +the target will belive it is running as the child, post-fork. + +This is defork.c from the amazing preeny project +https://github.com/zardus/preeny + +It is altered for afl++ to work with its fork-server: the initial fork will go through, the second fork will be blocked. diff --git a/examples/defork/defork.c b/examples/defork/defork.c new file mode 100644 index 00000000..f71d1124 --- /dev/null +++ b/examples/defork/defork.c @@ -0,0 +1,50 @@ +#define __GNU_SOURCE +#include <dlfcn.h> +#include <unistd.h> +#include <stdio.h> +#include <stdbool.h> + +#include "../../include/config.h" + +/* we want to fork once (for the afl++ forkserver), + then immediately return as child on subsequent forks. */ +static bool forked = 0; + +pid_t (*original_fork)(void); + +/* In case we are not running in afl, we use a dummy original_fork */ +static pid_t nop(void) { + + return 0; + +} + +__attribute__((constructor)) void preeny_fork_orig() { + + if (getenv(SHM_ENV_VAR)) { + + printf("defork: running in AFL++. Allowing forkserver.\n"); + original_fork = dlsym(RTLD_NEXT, "socket"); + + } else { + + printf("defork: no AFL++ detected. Disabling fork from the start.\n"); + original_fork = &nop; + + } + +} + +pid_t fork(void) { + + /* If we forked before, or if we're in the child (pid==0), + we don't want to fork anymore, else, we are still in the forkserver. + The forkserver parent needs to fork infinite times, each child should never + fork again. This can be written without branches and I hate myself for it. + */ + pid_t ret = !forked && original_fork(); + forked = !ret; + return ret; + +} + diff --git a/examples/defork/forking_target b/examples/defork/forking_target new file mode 100755 index 00000000..0f7a04fc --- /dev/null +++ b/examples/defork/forking_target Binary files differdiff --git a/examples/defork/forking_target.c b/examples/defork/forking_target.c new file mode 100644 index 00000000..98f6365a --- /dev/null +++ b/examples/defork/forking_target.c @@ -0,0 +1,48 @@ +#include <stdio.h> +#include <unistd.h> +#include <stdint.h> +#include <sys/types.h> + +/* This is an example target for defork.c - fuzz using +``` +mkdir in; echo a > ./in/a +AFL_PRELOAD=./defork64.so ../../afl-fuzz -i in -o out -- ./forking_target @@ +``` +*/ + +int main(int argc, char **argv) { + + if (argc < 2) { + + printf("Example tool to test defork.\nUsage ./forking_target <input>\n"); + return -1; + + } + + pid_t pid = fork(); + if (pid == 0) { + + printf("We're in the child.\n"); + FILE *f = fopen(argv[1], "r"); + char buf[4096]; + fread(buf, 1, 4096, f); + uint32_t offset = buf[100] + (buf[101] << 8); + char test_val = buf[offset]; + return test_val < 100; + + } else if (pid < 0) { + + perror("fork"); + return -1; + + } else { + + printf("We are in the parent - defork didn't work! :( (pid=%d)\n", + (int)pid); + + } + + return 0; + +} + |